Method and apparatus for the production of helical seam pipe

ABSTRACT

Apparatus is provided for forming a generally cylindrical pipe having a helical welded seam from a continuous strip of metallic material, said apparatus comprising a pipe forming mechanism which includes a plurality of individually adjustable bending rollers, means for feeding the strip to the pipe forming mechanism, measurement means located upstream from the pipe forming mechanism for measuring various dimensions of the strip prior to its entry into the pipe forming mechanism, adjustable pipe guide means located downstream from the pipe forming mechanism and arranged to engage the formed pipe to adjust the angular position thereof relative to the pipe forming mechanism, and control means whereby signals derived from the measurement means may be applied to adjust the operative positions of the pipe guide means and of the bending rollers to insure that the bending operation occurs in a manner which is correlated to the dimensions of the strip being passed therethrough. Control signals derived from the measurement means are applied to control the bending operation through a control unit which, by delaying the application of the signals, correlates the bending function with the measured values of portions of the metal strip whose measurements are taken at locations upstream of the bending apparatus. The bending apparatus and the measuring apparatus each comprise a plurality of rollers arranged in rows parallel longitudinal axes. The metal strip passes obliquely of said longitudinal axes and the measurement thereof is taken along a line which is substantially parallel and equidistant from the longitudinal axes of the bending rollers.

United States Patent [191 Gebauer [451 Nov. 5, 1974 METHOD-AND APPARATUS FOR THE PRODUCTION OF HELICAL SEAM PIPE [75] Inventor: Hans Gebauer, Dortmund-Heme,

Germany [73] Assignee: Hoesch Maschinenfabrik Deutschland Aktiengesellschaft, Dortmund, Germany [22] Filed: Oct. 25, 1973 [21] Appl. No.: 409,719

[30] Foreign Application Priority Data Oct. 28, 1972 Germany 2253025 [52] US. Cl 72/12, 72/16, 72/17, 72/135, 72/170, 219/62, 228/17 [51] Int. Cl. B2lc 37/083 [58] Field of Search 72/135, 9, 10, ll, 12,

[56] References Cited UNITED STATES PATENTS 3,030,488 4/1962 Kuckens 219/62 3,146,331 8/1964 Schubert 72/135 X Primary Examiner-Milton S. Mehr Attorney, Agent, or FirmToren, McGeady and Stanger [57] ABSTRACT Apparatus is provided for forming agenerally cylindrical pipe having a helical welded seam from a continuous strip of metallic material, said apparatus comprising a pipe forming mechanism which includes a plurality of individually adjustable bending rollers, means for feeding the strip to the pipe forming mechanism, measurement means located upstream from the pipe forming mechanism for measuring various dimensions of the strip prior to its entry into the pipe forming mechanism, adjustable pipe guide means located downstream from the pipe forming mechanism and arranged to engage the formed pipe to adjust the angular position thereof relative to the pipe forming mechanism, and control means whereby signals derived from the measurement means may be applied to adjust the operative positions of the pipe guide means and of the bending rollers to insure that the bending operation occurs in a manner which is correlated to the dimensions of the strip being passed therethrough. Control signals derived from the measurement means are applied to control the bending operation through a control unit which, by delaying the application of the signals, correlates the bending function with the measured values of portions of the metal strip whose measurements are taken at locations upstream of the bending apparatus. The bending apparatus and the measuring apparatus each comprise a plurality of rollers arranged in rows parallel longitudinal axes. The metal strip passes obliquely of said longitudinal axes and the measurement thereof is taken along a line which is substantially parallel and equidistant from the longitudinal axes of the bending rollers.

9 Claims, 12 Drawing Figures PMENIEBIM 5 m4 SHEET 3 BF 6 FIG. 5'

BACKGROUND OF THE INVENTION The present invention relates generally to the production of pipe formed in a generally cylindrical configuration from a substantially continuous metallic strip which is wound into a helical form and which has its edges joined by welding along a substantially continuous helical seam. More particularly, the invention is concerned with apparatus including a system of bending rollers which constitute the pipe forming mechanism of the apparatus.

Generally, such bending apparatus have, in the past, included a triad of bending rollers wherein one roller is located on the radially inner or outer side of the material forming the pipe wall with the other two rollers being located'on the opposite side thereof. in such known devices, scanners arranged at the outlet of the bending roll system have been utilized for controlling adjustment of the innermost roller of said triad of bending rollers by measuring deviations from a desired pipe wall curvature. Inasmuch as the sheet material from which the pipe is formed invariably involves significant dimensional deviation, disadvantages arise in such prior art devices in that the measured values determined by the scanner used for controlling the formation of the pipe are applied to bend a section of the metal strip which will very likely have dimensions which are different from the strip section at which the measured values were obtained. This is due primarily to thickness differences in the longitudinal and transverse directions of the sheet.

The present invention is aimed primarily at providing a method and apparatus of the aforementioned type for overcoming problems encountered in prior art devices, particularly with respect to the aforementioned disadvantages. ln the present invention, the metal strip from which the pipe is formed is measured prior to its entry into the pipe forming mechanism and control impulses obtained from the measured values of the strip are utilized to adjust the pipe forming mechanism and to change the position of pipe guide means arranged downstream of the pipe forming mechanism. The control impulses are applied with a predetermined delay interval which is determined by the time required for portions of the metal strip at which measurements are taken to reach the bending apparatus from the measurement site. In this manner, it is possible to control the operation of the pipe forming mechanism in a manner determined by measurements taken at a strip section which reaches the pipe forming mechanism at the time that the control impulses related to that strip section are applied as a control function.

The pipe forming mechanism of the invention comprises a system of rollers arranged along a longitudinal axis. In an embodiment of the invention, the measurements of the metal strip are most advantageously taken along a line which is substantially parallel and equidistant to such an axis of the pipe forming mechanism. Dimensional deviations from a given mean sheet thickness, which experience has shown can not be eliminated over the length or width of the strip, are thus determined in a manner which permits a direct correlation between the measuring points without requiring complicated conversion processes or devices, such as I would be necessary, for example, if the measured values were obtained along the line extending substantially parallel to thelateral edges of the strip, in which case the longitudinal axis of the strip measuring mechanism and the axis of the pipe forming mechanism would extend at an angle relative to each other.

SUMMARY OF THE INVENTION Briefly, the present invention may be described as apparatus for producing helical seam pipe from an endlessly welded metal strip comprising a pipe forming mechanism including a plurality of individually adjustable bending rollers, said bending rollers including a triad arrangement wherein one roller of said triad is located on one side of the metal strip with the remaining two rollers of the triad being located on an opposite side of the strip. The pipe forming mechanism operates to bend the metal strip in a helical pattern to form a generally cylindrical pipe therefrom. The apparatus also includes means for feeding the strip to the pipe forming mechanism, measurement means located upstream from the pipe forming mechanism for measuring the strip prior to entry into the pipe forming mechanism, adjustable pipe guide means located downstream from the pipe forming mechanism arranged to engage the formed pipe to adjust the angular position thereof relative to the pipe forming mechanism, adjustment means for effecting adjustment of the bending rollers and of the pipe guide means, means for generating control signals representative of the measured values of the strip taken by the measurement means, means for transmitting the control signals to the adjustment means to determine the positions of the bending rollers and of the pipe means in dependence upon the measured values, and means for controlling transmission of the control signals to the adjustment means in a timed relationship to correlate operation of the bending rollers and of the pipe guide means with the portions of the strip at which measured values represented by the control signals are taken.

A further aspect of the invention involves a structure wherein the measurement means are formed to include a plurality of measuring rollers and adjustable measuring beams upon which the rollers are mounted. Furthermore, in the apparatus according to the invention, each of the measuring rollers is arranged to be correlated to a specific one of the bending rollers of the pipe bending mechanism.

ln a device according to the present invention, an advantageously rapid resetting thereof to adapt the device to different metal strip thicknesses and pipe diameters may be achieved by determining the outside radius of individual measuring rollers in accordance with the ratio between the outside radius of the corresponding bending rollers and a radius of curvature of a metal strip having a mean strip thickness which is deformed by the bending roller.

A reliable coordination of the measured values with respect to the regions of the metal strip at which the measurements are taken can be insured by providing one measuring roller within the measurement means which consists of a friction roller which is held constantly in contact with one edge of the metal strip. The friction roller is connected with counter means for determining longitudinal units of length of the metal strip passing the friction roller thereby to determine the po-- sition within the apparatus of a specific strip region at which measurements are taken.

In an alternative embodiment of the invention, the friction roller and counter means may be replaced by an optical recording device which is arranged to sense markings provided on the metal strip to determine the relative location of specific portions of the strip length within the apparatus.

The various features of noveltywhich characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a schematic top view of apparatus in accordance with the present invention;

FIG. 2 is a sectional view through the metal strip taken along the line IIII of FIG. 1;

FIG. 2a is a sectional view taken along the line IIa-lla of FIG. 2 showing the welded strip ends;

FIG. 3 is an angular sectional view taken along the line IIIIII of FIG. 1, illustrating the metal strip measuring device of the invention;

FIG. 4 is a sectional view taken along the line IV-IV of FIG. 1 through the metal strip measuring device;

FIG. 5 is a longitudinal sectional view taken along the line VV of FIG. 1, illustrating the pipe forming mechanism on an enlarged scale wherein the bending rollers of the mechanism with their holding means are located in a position parallel to the axis of the pipe to be formed;

FIG. 6 is a sectional view taken along the line Vl-Vl of FIG. 5;

FIG. 7 is a top view of a metal strip section with bending rollers and driver rolls of the apparatus schematically shown thereon;

FIG. 8 is'a side view of the parts shown in FIG. 7;

FIG. 9 is a top view of a metal strip section with a butt welded joint and showing a parallel displaced track of the bending plane;

FIG. 10 is a side view of the parts shown in FIG. 9, illustrating thickness differences existing in the longitudinal direction of the metal strip; and

FIG. 11 is a sectional view taken along the line Xl-XI of FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein like reference numerals indicate similar parts throughout the various figures thereof, a continuous metal strip10 is produced in any desired length from sheets 13 having a thickness d, a length e and a width f (see FIGS. 7 and 8) by welding the machined ends 14, 15 of the strip. The apparatus operates to produce a generally cylindrical pipe 101 having a helical welded seam, and the requirement for maintaining with accuracy a desired inside or outside diameter for the pipe 101 determines whether the machined ends 14, 15 (see FIGS. 2a and 10) are aligned and welded with each other along their upper or lower abutting surfaces 141, 151 and 142,

152, respectively. The portions of the apparatus for working and welding the metal ends 14 and 15 are not shown, nor'is there shown the device for working the strip edges 11, 12 of the metal strip 10 composed of the sheets 13.

A feeding mechanism 20 imparts to the continuous metal strip a predetermined velocity in the feeding direction Z and feeds the strip 10 to a pipe forming mechanism 40. Between the feedmechanism 20 and the pipe forming mechanism 40 there is arranged measurement means in the form of a metal strip measuring device 30 (see FIGS. 1, 3 and 4) for measuring strip thickness,

longitudinal straightness and strip width. The strip measuring device 30 is connected with measuring elements 301- 311 over connecting lines 501-511 to a control unit 50, which comprises a signal modulator 50, a lag element and an impulse generator 60, with the unit being connected to measuring elements 461, 471, 432 (see FIGS. 1, 3, 4, 5 and 6). The pipe forming mechanism 40 combines (see FIGS. 1, 5 and 6) two outer bending rolls and one inner bending roll in a triad roll system. Each bending roll includes a plurality of individual bending rollers 41, 44 and 45. In the example of the present embodiment disclosed herein, only the inner bending rollers 41 are individually adjustable in height, with each inner bending roll 41 being connected to an associated adjusting means 46 as well as to a measuring element 461 (see FIG. 5). The measuring elements 461 are connected individually over a connecting line 512, with the adjusting means 46 being similarly individually connected over a connecting line 601, to the control unit 50, 60 which is connected to an electrical supply source. The strip measuring device 30 is located in a parallel-axis arrangement and equidistant to the bending rolls of the pipe forming mechanism 40 consisting of the bending rollers 41, 44 and 45 (see FIG. 1).

In order to enable measurement of the strip thickness d, spring loaded measuring rollers 321-326 are arranged on adjustable measuring beams 331-336 (see FIGS. 3 and 4). On the downstream side of the pipe forming mechanism 40 there is arranged an adjustable pipe guide mechanism 43, which may, for example, comprise a pipe backrest (see FIG. 1), which is coupled with shifting means 431 connected by a connecting line 602 to the control unit 50, 60. Spring loaded measuring rollers 341-344 (see FIGS. 1, 4) serve to determine the strip width and the longitudinal straightness of the strip 10. The measuring rollers 321-326, as well as rollers 341-344, are provided with associated measuring elements 301-310 (see FIGS. 1, 3 and 4) for connection to the control unit 50, 60. The measuring rollers 321,

.of the metal strip 10. A counter mechanism 3421 is connected to the measuring roller 342 in order to enable measurement of the length of the strip edge 11 passing the roller 342. The measuring element 311 is coupled with the counter 3421 (see FIG. 3) and serves to correlate the values determined by the measuring elements 311-310 with the respective points on the metal strip where such measured values are taken. Thus, by measuring the length of the strip passing through the measuring means 30, a correlation may be drawn which will enable a determination of the point at which a section of strip at which measured values are taken reaches the pipe forming mechanism 40. This correlation enables the measured values which are taken at a point upstream from the pipe forming mechanism 40 to be later applied to control operation of the pipe mechanism 40 at the time when the section of the metal strip represented by the measured values reaches the pipe forming mechanism.

In an alternative embodiment of the present invention, the mechanical counter 3421 may be replaced by an optical recording device (not shown) which operates to sense markings which may be applied along the length of the metal strip 10 as longitudinal units of length, for example, a pilot band, and which may be connected over the measuring element 311 and through the connecting line 511 to the control unit 50, 60.

At the commencement of the operation of the apparatus, an inner arm 42 carrying the bending rollers 41 and retaining rollers 47 (see FIG. 6) is set to a desired outside pipe diameter. The outer bending rollers 44, 45 are oriented to be substantially parallel to the strip edges 11, 12 over the roller beams 441, 451 (see FIG. 6) which are displaceable in an axial direction relative to the welded pipe 101. In order to determine the outside diameter of the pipe 101, the retaining rollers 47 are equipped with measuring elements 471 which are connected through connecting lines 513 to the control unit 50, 60.

The metal strip 10, having its edges 11, 12 prepared for a welding operation therealong, is engaged within the feeding means and the feed rollers 21, 22 thereof (see FIGS. 1, 7 and 8) which are driven at a variable speed through operation of the control unit 50, 60 impart to the metal strip 10 a predetermined feed velocity in the direction of the pipe forming mechanism 40, due to the friction forces prevailing in an undesignated rolling gap. An imaginary plane 12, which lies between the axes of rotation 211, 221 of the feed rollers 21, 22 (see FIG. 7) extends with regard to the metal strip 10 substantially parallel to a plane (not shown) which lies between the center axes of the working rolls of the roll stand performing the last pass on the respective sheet 13. After leaving the feeding means, the front edge of the strip 10 arrives in the metal strip measuring device (see H08. 1, 3 and 4) and is thereby positioned within a measuring gap formed between upper measuring rollers 324, 325, 326 and lower measuring rollers 321, 322, 323, as well as between measuring rollers 341-344 arranged on both sides of the metal strip 10.

The sheet thickness values determined in the gap between the upper and lower measuring rollers 321 326 are transmitted through the measuring elements 301-306 to the control unit 50, 60 where they are stored. The measuring friction roller 342 provided with the counter means 3421, transmits path coordinates to the control unit 50, 60 in a manner effected in a given rhythm or continuously.

The laterally arranged measuring rollers 307-310 transmit to the control unit 50, 60 data representing the width and longitudinal straightness of the metal strip 10 with the data being stored in the control unit. After leaving the strip measuring device 30, the forward edge of the metal strip 10 arrives to within the range of the pipe forming mechanism 40 and becomes engaged within the system comprised of the bending rolls including the individual bending rollers 41, 44, 45. A central axis (not shown) of the aforementioned triad bending roll system is arranged parallel to the central axis (also not shown) of the strip measuring device 30. When the leading or front edge of the metal strip 10 has reached the triad roll system of the pipe forming mechanism 40, the control unit 50, emits control impulses which represent the stored values of the previously developed measurements of the metal strip 10, to the bending rollers 41, 44 and 45, which are associated with the respective correlated measuring rollers of the strip measuring device 30 (see FlGS. 1, 3 and 4). With corresponding processing of the values represented by the path coordinates transmitted by the counter 3421, and through the action of the lag element arranged in the control unit 50, 60, the bending rollers 41 are adjusted by their respective adjusting elements 46 in such a manner that their adjustment corresponds to the linear portion of the metal strip 10 which has been located within the range of action of the pipe forming mechanism 40 on the basis of the values previously determined for that section of the metal strip in the strip measuring device 30. In this manner, the adjustment of the bending rollers is timed to coincide with the arrival thereat of a metal strip section which has been previously measured in the measuring device 30. Thus, any dimensional deviations for a measured section will be compensated for inasmuch as the adjustment of the bending rollers is effected in response to values derived for that specific strip section.

Metal strip 10 is thus deformed into a helical pattern wherein corresponding points on the strip edges 11 and 12 will be brought together accurately so that they may be welded to form a seam by means of an inner arc welding head 421 located on the radially inner side of the pipe and by means of an outer arc welding head 426 (see FIGS. 1, 5 and 6) located on the outer radial side. Thus, a cylindrical pipe 101 may be formed with a helical welded seam.

The welded pipe 101 emerges from the pipe forming mechanism 40 and is immediately received by a pipe guide member 43 which at least partially supports the pipe 101 at a location proximate the vicinity of the pipe forming mechanism 40. The pipe guide 43 is equipped with a shifter 431 and a measuring element 432 which is connected through a connecting line 514 to the control unit 50, 60 (see FIG. 1). The guide member 43 operates to position the pipe 101 in such a manner that the strip edges 11 and 12 which are to be welded together become positioned under the welding head 421 in an appropriate lateral location to facilitate the welding operation. Changes in the position of the guide member 43 are effected by the shifter 431 which is connected to the control unit 50, 60. By changing the position of the guide 43, it is possible to vary the diameter of the pipe 101 being formed. As will be seen from F IG. 1, the strip edge 11 forms an angle alpha, referred to as the feed angle, with a projection of the generatrix of the pipe 101 projected in the plane of the drawing, which angle alpha is greater than 90 and less than In the example depicted herein. the actual feed angle is determined by the values measured through the measuring members 432, 307, 308, and 309 (see FIG.

l) with the correcting control impulses derived therefrom being transmitted by the control unit 50, 60 to the shifter 431 in order to adjust the positioning of the guide member 43 and thereby control the specific angle which the pipe 101 generates relative to the strip feeding direction.

As is well known, differences in strip thickness will appear in the rolling of metallic sheets both with regard to the direction of rolling and directions transversely thereof. In the rolling operation, tolerances greater or less than a predetermined standard value are common place and are usually controlled by operating personnel in steel manufacturing facilities. Generally, thickness dimensions which vary from the nominal or standard value within acceptable limits are invariably tolerated in the production of sheet material. As a result, it is not unlikely that two sheets, such as the sheets 13, welded together in a butt welded arrangement as shown in FIGS. 9 and 10, will differ significantly in thickness along portions of their edges 14 and 15. Furthermore, as will be seen from FIG. 10, thickness differences appearing over the length of the sheet, i.e., in the direction of sheet rolling, will result in special requirements with regard to the settings of the elements of the pipe forming mechanism 40. With reference to a track a of the bending plane of the pipe forming mechanism 40 shown in FIGS. 7 and 9, there may be obtained for a section following a track a a considerable thickness difference labelled d d. In order to enable handling of such unavoidable irregularities in thickness differences extending either in the rolling direction or in the transverse direction of the sheet, as well as thickness variations at the transverse butt joint, the strip measuring device 30 and the pipe forming mechanism 40 are arranged in a manner whereby the axes of the respec tive elements of the device are maintained in a parallel and equidistant relationship with regard to the measuring and bending elements. As previously mentioned, such an arrangement between the strip measuring device 30 and the pipe forming mechanism 40 simplifies the correlation between control impulses derived from measured values of specific sections of strip material with those values being applied to control the bending mechanism when the strip section represented by such control impulses is received by the bending device. The requirement for such an approach in the bending of helical seam pipe is particularly advantageous when the aforementioned thickness differences extending in a rolling direction and in the transverse direction of the sheet, as well as thickness variations at the transverse butt joint, are taken into consideration. By applying the arrangement and methods of the present invention, there may be avoided many of the disadvantages previously discussed in connection with dimensional variations which arise in the state of the art devices.

The embodiment of the present invention disclosed herein enables the production of helical seam pipe with small tolerances being maintained in the outside diameter of the pipe. For this reason, only the inner bending rollers 41 are made individually adjustable in height by the adjusting means 46. If it is desired to produce helical seam pipe with small tolerances in the inside diameter of the pipe, the outer bending rollers 44 and 45 may be adjusted by the appropriate controls which will require the inclusion of corresponding adjusting means.

Strip thickness differences can be readily measured in a proper manner with one upper and one lower measuring beam 335, 332. By providing three upper and three lower measuring beams 334, 335, 336, 331, 332, 333, the processing of the measured values is facilitated particularly with regard to control of the guide member 43, since strip thickness differences also will influence the feed angle alpha which must be adjusted accordingly.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. A method for producing helical seam pipe from an endlessly welded metal strip, said metal strip being shaped into a generally cylindrical pipe in a pipe forming mechanism including a triad of bending rollers wherein one of said rollers is positioned on one side of said strip and two of said rollers are positioned on the opposite side of said strip, with pipe guide means arranged to engage said formed pipe to adjust the angular position thereof relative to said pipe forming mechanism, said method comprising the steps of feeding said strip to said pipe forming mechanism, measuring said strip prior to its entry into said pipe forming mechanism, deriving control signals from the measured values of said strip, applying said derived signals to control the operating positions of both said pipe forming mechanism and said pipe guide means, and delaying said application of said control signals for preselected periods corresponding to the time required for portions of said strip at which said measured values are taken to travel from said measuring location to said pipe forming mechanism and said pipe guide means, respectively.

2. A method according to claim 1, wherein said pipe forming mechanism comprises a longitudinal axis and wherein said measurement of said strip is taken along the line extending parallel to and equidistant from said longitudinal axis.

3. Apparatus for producing helical seam pipe from an endlessly welded metal strip comprising: a pipe forming mechanism including a plurality of individually adjustable bending rollers, said bending rollers including a triad arrangement wherein one roller of said triad is located on one side of said strip with two rollers of said triad being located on an opposite side of said strip, said pipe forming mechanism operating to bend said metal strip in a helical path to form a generally cylindrical pipe therefrom; means for feeding said strip to said pipe forming mechanism; measurement means located upstream from said pipe forming mechanism for measuring dimensions of said strip prior to entry of said strip into said pipe forming mechanism; adjustable pipe guide means located downstream from said pipe forming mechanism arranged to engage said formed pipe to adjust the angular position thereof relative to said pipe forming mechanism; adjustment means for effecting adjustment of said bending rollers and of said pipe guide means; means for generating control signals representative of the measured values of said strip dimensions taken by said measurement means; means for transmitting said control signals to said adjustment means to determine the positioning of said bending rollers and of said pipe guide means in dependence upon said measured values; and means for controlling transmission of said control signals to said adjustment means in a timed relationship to correlate operation of said bending rollers and of said pipe guide means with the portions of said strip at which measured values represented by said control signals are taken.

4. Apparatus according to claim 3, wherein said measurement means comprise a plurality of measuring rollers and adjustable measuring beams having said rollers mounted thereon.

5. Apparatus according to claim 4; wherein there is provided a measurement roller of said measurement means positioned to have its function correlative to each one of said bending rollers of said pipe forming mechanism.

6. Apparatus according to claim 5, wherein said measuring rollers each comprise an outside radius which is derived from the ratio between the outside radius of the bending roller correlated thereto and the radius of curvature of a metal strip having a mean strip thickness deformed by said correlated bending roller.

7. Apparatus according to claim 3, wherein said measurement means include at least one measurement roller which is a friction roller maintained in constant contact with one edge of said metal strip.

8. Apparatus according to claim 7, including counter means operatively connected with said friction roller for measuring the length of said metal strip.

9. Apparatus according to claim 3, wherein said metal strip has applied thereto markings representing units of length of said strip and wherein said measuring means include optical sensing means operative to sense said markings to measure the length of said strip. 

1. A method for producing helical seam pipe from an endlessly welded metal strip, said metal strip being shaped into a generally cylindrical pipe in a pipe forming mechanism including a triad of bending rollers wherein one of said rollers is positioned on one side of said strip and two of said rollers are positioned on the opposite side of said strip, with pipe guide means arranged to engage said formed pipe to adjust the angular position thereof relative to said pipe forming mechanism, said method comprising the steps of feeding said strip to said pipe forming mechanism, measuring said strip prior to its entry into said pipe forming mechanism, deriving control signals from the measured values of said strip, applying said derived signals to control the operating positions of both said pipe forming mechanism and said pipe guide means, and delaying said application of said control signals for preselected periods corresponding to the time required for portions of said strip at which said measured values are taken to travel from said measuring location to said pipe forming mechanism and said pipe guide means, Respectively.
 2. A method according to claim 1, wherein said pipe forming mechanism comprises a longitudinal axis and wherein said measurement of said strip is taken along the line extending parallel to and equidistant from said longitudinal axis.
 3. Apparatus for producing helical seam pipe from an endlessly welded metal strip comprising: a pipe forming mechanism including a plurality of individually adjustable bending rollers, said bending rollers including a triad arrangement wherein one roller of said triad is located on one side of said strip with two rollers of said triad being located on an opposite side of said strip, said pipe forming mechanism operating to bend said metal strip in a helical path to form a generally cylindrical pipe therefrom; means for feeding said strip to said pipe forming mechanism; measurement means located upstream from said pipe forming mechanism for measuring dimensions of said strip prior to entry of said strip into said pipe forming mechanism; adjustable pipe guide means located downstream from said pipe forming mechanism arranged to engage said formed pipe to adjust the angular position thereof relative to said pipe forming mechanism; adjustment means for effecting adjustment of said bending rollers and of said pipe guide means; means for generating control signals representative of the measured values of said strip dimensions taken by said measurement means; means for transmitting said control signals to said adjustment means to determine the positioning of said bending rollers and of said pipe guide means in dependence upon said measured values; and means for controlling transmission of said control signals to said adjustment means in a timed relationship to correlate operation of said bending rollers and of said pipe guide means with the portions of said strip at which measured values represented by said control signals are taken.
 4. Apparatus according to claim 3, wherein said measurement means comprise a plurality of measuring rollers and adjustable measuring beams having said rollers mounted thereon.
 5. Apparatus according to claim 4, wherein there is provided a measurement roller of said measurement means positioned to have its function correlative to each one of said bending rollers of said pipe forming mechanism.
 6. Apparatus according to claim 5, wherein said measuring rollers each comprise an outside radius which is derived from the ratio between the outside radius of the bending roller correlated thereto and the radius of curvature of a metal strip having a mean strip thickness deformed by said correlated bending roller.
 7. Apparatus according to claim 3, wherein said measurement means include at least one measurement roller which is a friction roller maintained in constant contact with one edge of said metal strip.
 8. Apparatus according to claim 7, including counter means operatively connected with said friction roller for measuring the length of said metal strip.
 9. Apparatus according to claim 3, wherein said metal strip has applied thereto markings representing units of length of said strip and wherein said measuring means include optical sensing means operative to sense said markings to measure the length of said strip. 